In recent years, an IC card equipped with a non-volatile memory and other functions was developed, and has spread through the market. For example, a technique of mounting an IC card equipped with a flash memory and a television broadcast receiving function on a PDA (Personal Digital Assistants), transmitting the visual data and the audio data which the IC card received to the PDA, and outputting it from the PDA display and the speaker, is about to be realized.
Generally, data transmission between a main unit of an equipment (will refer to as a “data transmission apparatus” in this description) and an IC card is executed in a master/slave mode communication in which the data transmission apparatus is assumed as master. Conventionally, the data transmission apparatus executed a request-to-send and a confirmation of receipt for each data that is to be a transmission unit when reading out data from the IC card.
An IC card of the conventional art in accordance with the Official Gazette of Japanese Unexamined Patent Publication Hei 10-27231 divides data into a plurality of blocks corresponding to the size of a receiving buffer of a terminal (data transmission apparatus). Then, the IC card further divides the block into data with the size of a sending buffer of its own, and sends the data sequentially to the terminal. The terminal sends a “continuation data demanding block” to the IC card each time the terminal receives all the data which composes a single block. The IC card of the conventional art can transmit data to the terminal in high-speed when the IC card has the sending buffer which is smaller in size than the size of the receiving buffer of the terminal.
As the intended use of the IC card expands to equipments in which its memory capacity of a buffer memory for a two-way transmission is small, and its processing capability is low, the need to use a more effective and high-speed data transmission method rose.
In the IC card of the conventional art in accordance with the Official Gazette of Japanese Unexamined Patent Publication Hei 10-27231, the communication speed was extremely slow when the size of the sending buffer is larger than the size of the receiving buffer of the data transmission apparatus. In such a case, the IC card of the conventional art divided the data packet into a plurality of blocks wherein the size of the block is equal to or smaller than the size of a receiving buffer of the terminal. The terminal sends the “continuation data demanding block” to the IC card, each time the terminal receives one block. Since there is a need to confirm whether the transmission between the terminal and the IC card was executed normally whenever a block is transmitted, its communication speed was slow. Such data transmission method placed heavy burden on an audiovisual equipment such as a digital camera and the like, which is low in processing capability.
The present invention solves the above-mentioned conventional problems, and aims to provide an IC card, a data transmission apparatus, a data transmission method and a computer program of data transmission method that can transmit data in high-speed between an IC card and a data transmission apparatus even when the processing capability of the data transmission apparatus is low.
Furthermore, it aims to provide an IC card, a data transmission apparatus, a data transmission method and a computer program of data transmission method that can transmit data corresponding to the memory capacity of a buffer memory for a two-way transmission of a data transmission apparatus.